V. P. Vorob’eva

Bond Dissociation Energies of Nitroethanes and Their Radicals

Based on control experiments and published data, the thermochemical characteristics of ethane nitroderivatives in the standard state and in the gas phase were recommended. The dissociation energies of the bonds in polynitroethanes were determined from the energies of the nonvalence interactions of nitro groups with each other and compared to the available kinetic data. The energies of the nonfunctional interaction of nitro groups were used to calculate the dissociation energies of bonds in nitroethyl radicals.

Parametric and matrix algorithms for calculating heterogeneous states in systems with an incongruently melting binary compound

A matrix description of the crystallization process is proposed, according to which all transformations of a melt can be presented as a set of products of the matrices of phase compositions and the vectors comprised of the mass fractions of the phases. It was demonstrated that this approach is simpler, more illustrative, and more versatile in predicting the microstructure of heterogeneous materials compared to the traditional methods of solving the problems involving center-of-mass determination. An algorithm for calculating the characteristics of two-phase equilibria based on parametric equations of its boundaries in isobaric-isothermic sections is given.

Verification of the T–x–y diagram of the Ag–Au–Bi system using a 3D computer model

Using two variants (with and without decomposition of the compound Au2Bi) of a 3D computer model of the T–x–y diagram of the system Ag–Au–Bi, it was shown that the published polythermal sections (both experimental and calculated by the CALPHAD method) agree in the high-temperature range of the T–x–y diagram for phase regions with melt, whereas in the low-temperature range the decomposition of a solid solution based on the compound Au2Bi is not taken into account.

3D model of the T–x–y diagram of the Bi–In–Sn system for designing microstructure of alloys

The published experimental and calculated data (binary systems, x–y projection of the liquidus, table of invariant reactions with the liquid phase, and one isothermal and two polythermal sections) were used for constructing a spatial computer model of the T–x–y diagram of the Bi–In–Sn system that was supplemented with the regions of the decomposition of the compound BimInn and the polymorphic transformation of tin. It was determined that the T–x–y diagram comprises 173 surfaces and 74 phase regions. Using the model for analyzing the material balances of phases and their microstructural components at all the stages of crystallization was demonstrated.

Three-dimensional model of phase diagram of Au-Bi-Sb system for clarification of thermodynamic calculations

A three-dimensional (3D) computer model of a T–x–y-diagram for an Au-Bi-Sb system is developed. It is established that it consists of 60 surfaces and 24 phase areas. It is used to show that works devoted to experimental studies and thermodynamic calculations of this system miss two surfaces and two phase areas in the iso- and polythermic sections.

Determining the conditions for changes of the three-phase reaction type in a V‒Zr‒Cr system

A 3D computer model of the T–x–y diagram for a V–Zr–Cr system is constructed, in which the possibilities of both two- and three-polymorphic modifications of compound ZrCr2 participating in invariant reactions is considered. The temperature and concentration borders of eutectic–peritectic transitions in the three-phase regions on the corresponding surfaces of two-phase reactions are determined (upon degeneration of a three-phase reaction into a two-phase reaction in the presence of the third phase).

Search for internal diagonals in polyhedration of reciprocal systems by the algorithm for topological correction of lists of simplexes of different dimensions

The algorithm for topological correction of lists of simplexes of different dimensions was used for analyzing the published methods for determining internal diagonals in polyhedration of reciprocal systems. By this algorithm, errors were found in the polyhedration of the quaternary systems Ca,Na,K‖F,MoO4, K,Na,Li‖Cl,NO3, Ba,Na,K‖F,MoO4, Na,K‖Cl,NO3,NO2, and Li,K,Ba‖F,WO4 and the quinary system Li,K,Ca,Ba‖F,WO4, which were used for illustrating the application of the methods. Advantages of the algorithms were demonstrated in cases of competition of internal secants.

Triangulation of salt systems with barium borate

A program has been developed that implies the following operations: vertices of an n-component system are presented in the form of a graph, the adjacency matrix and the adjacency list with zero adjacencymatrix elements are written, the elements of the adjacency list are multiplied taking into account the absorption rule, and inversion is performed. The local X(x1, …, xm) barycentric coordinate subsystems in the unified space of an n-component system Z(z1, …, zn) are related by the equation Z = KX, where the Z coordinates of subsystem vertices are located in the columns of the matrix K [m × n]. The membership of the composition G(g1, …, gn) in subsystem K is determined by the condition 0 < xi < 1 for the roots of the equation G = KX. When recognizing the simplices formed by internal vertices, polyhedration is performed twice: first without these points and then only with respect to the microcomplexes with internal points. Formulas that relate the number of obtained simplices to the adjacency matrix have been derived to verify the results of polyhedration.

3D Computer Models of T – x – y Diagrams, Forming the Fe–Ni–Co–FeS–NiS–CoS Subsystem

Abstract3D computer models of Fe–Ni–Co, Fe–Ni–FeS–NiS, Fe–Co–FeS–CoS, Ni–Co–NiS–CoS T–x–y diagrams have been designed. The geometric structure (35 surfaces, two-phase surface of the reaction type change, 17 phase regions) of the Fe–Ni–FeS–NiS T–x–y diagram is investigated in detail. The liquidus hypersurfaces prediction of the Fe–Ni–Co–FeS–NiS–CoS subsystem is represented.

Algorithm for topological correction of lists of simplexes of different dimensions for polyhedration of multicomponent systems

A new algorithm for polyhedration of quaternary and quaternary reciprocal systems is presented. The algorithm is based on checking all the links between vertices of a graph describing the composition diagram and selecting the polyhedration variants that correspond to the relations between the numbers of geometric elements of the complex undergoing polyhedration (graph vertices, links between them, and two-and three-dimensional complexes). Unlike Kraeva’s algorithm based on the decomposition of the graph in terms of zero elements of the adjacency matrix (absent links between vertices), the new algorithm can control the entire polyhedration process, accelerates the search for internal diagonals in the polyhedron, and takes into account their possible competition.